Conversion Question

Discussion in 'Homework Help' started by ElectronicsFanatic, May 6, 2012.

  1. ElectronicsFanatic

    Thread Starter Member

    Feb 12, 2012
    30
    1
    For some reason I have really confused myself on how to do these homework assignments that are asking me to complete the conversions.

    Here is one:
    0.0001 MHz = ______Hz
    What is throwing me off is that it is saying .0001Mkz. I am thinking that i would need to reduce this number to make it smaller since Hz is smaller than MHz so I am coming up with this number:
    .1 x 10^-9

    Am I doing this right? I don't get the feeling that I am doing this right? Could you send some hints my way?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,456
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    ElectronicsFanatic likes this.
  3. ElectronicsFanatic

    Thread Starter Member

    Feb 12, 2012
    30
    1
    Ok I have looked at the metric system prefixes and what is confusing me so much is the fact that it says 0.0001Mhz. I haven't had to deal with decimals like this before. When it says Mhz I think 1,000,000. But the way that my brain is telling me is that this is supposed to be 100μHz but it is in Mhz with μHz notation.

    So if i follow the chart you provided i would need to get rid of 6 decimal places to make it 100Hz?
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,456
    2,287
    Hello,

    Yes, 100 Hz is the correct answer.

    Bertus
     
  5. ElectronicsFanatic

    Thread Starter Member

    Feb 12, 2012
    30
    1
    Ok, Thanks for the help. I know this is pretty easy, but I got myself all mixed up somehow and needed a push in the right direction again.
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,104
    3,249
    Use 1M = 10^6

    0.0001 = 10^{-4}

    Hence 0.0001M = 10^{(-4  +  6)} = 10^2 = 100
     
    Last edited: May 6, 2012
  7. WBahn

    Moderator

    Mar 31, 2012
    17,332
    4,662
    Here is one place where using the units can really help out. Here is one way to approach it:

    <br />
x Hz = 0.0001 MHz<br />

    Your goal is to find the value of 'x' that makes this expression true and you will accomplish by multiplying the right hand side by values of 1 (so the value is not changed) but choosing how you express the value of 1 such that the units do change.

    <br />
x Hz = 0.0001 MHz \ \times \ \frac{10^6 Hz}{1MHz}<br />

    Here we have just multiplied the right hand side by 1, since the numerator (10^6Hz) is equal to the denominator (1MHz).

    <br />
x Hz = (0.0001)(10^6) Hz \ \times \ \frac{1MHz}{1MHz}<br />

    Here we have just rearranged factors, nothing more.

    <br />
x Hz = 100 Hz<br />

    Here we have merely carried out the math and removed factors that cancel.

    Another way to approach it is to treat the prefix as what it is, a multiplier separate from what it is multiplying:

    <br />
x Hz = 0.0001 MHz<br />
x Hz = (0.0001)(M)(Hz)<br />
x Hz = (0.0001)(M)(Hz) \times \frac{10^6}{M}<br />
x Hz = \frac{(0.0001)(M)(Hz)(10^6)}{M}<br />
x Hz = (0.0001)(10^6)(Hz)<br />
x Hz = 100 Hz<br />
     
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